Search

Purpose: Smooth muscle cells of the vas deferens have an important role in carrying sperms to the exterior but little is known of their electrophysiological properties. We characterized the voltage-gated ion channel currents in single smooth muscle cells of the human vas deferens (HVSMCs). Materials and Methods: We observed contractile responses of 8 circular smooth muscle strips of the human vas deferens to a high concentration (10 mM) of tetraethylammonium. HVSMCs were isolated using proteolytic enzymes (collagenase and papain), and were used for an electro-physiological study using whole cell and inside-out patch clamp configurations. Results: The application of 10 mM tetraethylammonium induced rhythmic contractions of the strips. When HVSMCs were dialyzed with a KCl solution, step depolarizations of membrane potential evoked oscillatory outward K currents that were not inactivated. The large conductance Ca activated K (BK Ca ) and delayed rectifier components of the outward current were identified. The BK Ca channel showed a large single channel conductance (162.7 ± 13.2 pS with 5 mM K in the patch pipette). Two types of Ca currents were identified in the whole cell configuration. With a cell held at −50 mV an L-type Ca current was present during a depolarizing step pulse. From a holding potential of −90mV L-type and T-type Ca currents were elicited by depolarizing step pulses. Conclusions: HVSMCs have 2 (L and T) types of Ca channels and 2 types of K (BK Ca and delayed rectifier) channels. Voltage dependent changes of these ion channels and their interactions may be important in regulating vas contractility.

Purpose: To evaluate, in vivo, the inhibitory effects of certain serotonergic drugs on the contractile response of the rat seminal tract to electrical stimulation of the hypogastric nerve.Materials and Methods: Twenty-five Sprague Dawley rats (250 to 300 gm. each) were equally divided into 5 groups based on experimental agent; normal saline, clomipramine, sertraline, paroxetine, and fluoxetine. The hypogastric nerve was electrically stimulated and the intraluminal pressure of the vas deferens was measured, both pretreatment and 30 minutes after intravenous injection of four different doses (0.1 to 20 × the therapeutic dose) of each agent. Variations of responses relative to the time after administration of each agent (at 10- and 20-fold concentration) were also observed.Results: All serotonergic drugs caused dose-dependent inhibition of elevation in intraluminal pressure of the vas deferens (p